The objective of this project is to characterize dose-response relationships and toxicity of pentachlorophenol and oxazepam administered by dosed feed to rats. A 28-day study will be conducted for pentachlorophenol to provide data for the selection of doses to be used in the 2-year chronic study. For oxazepam, the 2-year chronic study will be conducted immediately since sufficient data for dose selection exist. All animals will be treated ad libitum during the course of the test period. At the end of each study, all animals will be given gross and microscopic histopathologic evaluations. Plasma samples are to be obtained from test animals prior to and at 8 timepoints after a single gavage dose on the day of necropsy in both chronic studies. These samples will then be evaluated under separate contract for determination of plasma concentrations of the test compounds.